Risk factor for axillary lymph node metastases in microinvasive breast cancer

Background: Sentinel lymph node biopsy (SLNB) in patients with ductal carcinoma in situ (DCIS) was controversial. Usually we did not do a SLN biopsy when we performed conserving operations with small-sized DCIS. However, sometimes we find DCIS with microinvasive breast cancer (MIC) after the operation. Must reoperations be performed in all patients? The incidence of axillary metastases in microinvasive breast cancer (MIC) has not been extensively studied. We determined the incidence of positive axillary lymph node (ALN) in patients with MIC and the predictive factors of ALN metastases in these patients. Methods: Between July 1989 and December 2008, 9635 patients had operation on invasive breast cancer in Asan Medical Center. Among these patients, 319 patients had MIC. The research conducted on the 293 patients (excluded were 26 who did not receive axillary lymph node dissection or SLN biopsy). We retrospectively checked clinical and pathologic variables. Results: There were 22 cases of ALN metastases identified in this group of patients (7.5%). Lymphatic invasion (P < .001) and positive estrogen receptor status (P = 03) were independent significant predictors of axillary metastases. Conclusions: Microinvasive breast cancer is associated with a low rate of lymph node metastases. Some breast cancer patients with MIC at low likelihood of lymph node metastases may be spared lymph node evaluation.